<p>Disordered eating behaviors (DEBs), characterized by abnormal eating behaviors patterns associated with body image disturbances or dysfunctional weight regulation, demonstrate complex etiological pathways involving psychosocial and familial determinants. Although prior research highlights family health as a protective factor against DEBs, the mediating mechanisms underlying this association remain insufficiently examined. This cross-sectional nationwide study investigated the sequential mediating roles of perceived social support and self-efficacy in the relationship between family health and DEBs among Chinese young adults. A representative sample of 11,031 participants (<i>M</i>_age = 23.53, <i>SD</i> = 4.24) completed validated self-report instruments: the Short-form Sakata Eating Behavior Scale (DEB assessment), Perceived Social Support Scale, Short-form Family Health Scale, and New General Self-Efficacy Scale. Serial mediation analyses using the PROCESS macro (Model 6) revealed three key findings: (1) Parental family health demonstrated a significant negative association with DEB severity; (2) Both perceived social support and self-efficacy independently mediated the family health-DEB relationship; and (3) Findings revealed a sequential mediation pathway where family health exerted a positive predictive effect on social support, which subsequently fostered self-efficacy—with the final outcome being a lowered risk of DEBs. Notably, this pathway varied significantly across different age cohorts. These results advance theoretical understanding of protective familial processes against DEBs by elucidating psychosocial mechanisms through which supportive family environments may foster interpersonal resources and intrapersonal competencies that buffer against disordered eating. Clinical implications emphasize integrated interventions targeting family dynamics, social support networks, and self-efficacy development.</p>